Hello, check if this works for you.
If what you are getting in Request.JSON is a String, put it this way:

ClassMethod Test() As %Status
{ 
SET Data = ##class(%Net.HttpRequest).%New() 
SET Obj = "{teste:1}"

DO Data.EntityBody.Write(Obj)
 
Quit 1
}

If you are receiving a Stream, do this:

DO Data.EntityBody.Write(Obj.Read())